Method and Apparatus for Compressing a Gaseous Medium

ABSTRACT

A method and apparatus for compressing a gaseous medium, specifically hydrogen, is disclosed. Compression is managed by a reciprocating piston compressor, where the piston or pistons of which have a dynamic seal or dynamic seals. A graphite-bearing medium is supplied to the cylinder chamber or chambers before and/or during compression, where the graphite-bearing medium is configured such that it settles on the dynamic seal or seals. The reciprocating piston compressor has a means to supply/introduce the graphite-bearing medium into the cylinder chamber or chambers.

This application claims the priority of International Application No. PCT/EP2005/010148, filed Sep. 20, 2005, and German Patent Document No. 10 2004 046 340.9, filed Sep. 24, 2004, the disclosures of which are expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a method for compressing a gaseous medium, specifically hydrogen, wherein compression is carried out by a reciprocating piston compressor, the piston(s) of which have a dynamic seal or dynamic seals.

The invention further relates to a reciprocating piston compressor having one or more cylinder chambers, wherein the piston or pistons have dynamic seals.

With methods of a generic kind for compressing a gaseous medium and with reciprocating piston compressors of a generic kind, as they are used, for example, in the compression of natural gas or hydrogen, signs of wear appear on the dynamic seals after about 500,000 cycles. These unavoidable signs of wear result in a reduction of power and can, under certain circumstances, lead to a failure of the reciprocating piston compressor. Dynamic seals must, therefore, be replaced at regular intervals at comparatively great expense. The term “dynamic seal” is usually understood to mean seals which undergo a sliding movement and must be tight.

Normally, the life and thus the replacement cycle for a dynamic piston seal is normally determined from the recorded number of cycles of a piston and when a specified number of cycles is reached, or to the extent the compression performance drops before the specified number of cycles is reached, the dynamic seal is replaced. Replacement means, however, not only maintenance and investment costs but in addition unwanted downtime.

The object of the present invention is to specify a method of a generic kind for compressing a gaseous medium and also a reciprocating piston compressor of a generic kind in which the maintenance intervals can be extended and thus the costs of its operation, specifically the maintenance costs, can be reduced.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The characteristic of the method in accordance with the invention is to supply a graphite-bearing medium to the cylinder chamber or chambers before and/or during compression, where the graphite-bearing medium is composed such that it attaches itself to the dynamic seal or seals.

The characteristic of the reciprocating piston compressor in accordance with the invention is that means are provided for supplying a graphite-bearing medium to the cylinder chamber or chambers.

Graphite dust, molybdenum and/or other dusts or dust mixtures which possess lubricating properties are advantageously used as the graphite-bearing medium.

For example, graphite, tallow, cotton fluffs, nut shell granulate, sawdust, etc. are used as dusts or dust mixtures which possess lubricating properties.

Refining the method in accordance with the invention for compressing a gaseous medium, it is provided that at least one sealing additive such as for example, cotton fluffs, mustard fiber and/or other additives which tend to clog and/or clump, such as for example, sawdust, plastic granulate, nutshell granulate be added to the graphite-bearing medium.

When a graphite-bearing medium is introduced into a cylinder chamber, this medium is distributed on the inner surfaces or walls of the cylinder. Through the movement of the piston, the graphite-bearing medium attaches itself to the leaking areas of the dynamic seal(s) and thereby closes or seals them. In addition to this, the graphite-bearing medium forms a lubricating film on the cylinder inner wall or the piston wall.

The aforementioned addition of sealing additives, such as for example, cotton fluffs, etc. to the graphite-bearing medium reinforces the sealing effect described previously.

The introduction of the graphite-bearing medium, into which at least one sealing additive is blended if required, into the cylinder chamber or chambers can be advantageously carried out by means of compressed air, the gas itself—meaning the gas (mixture) to be compressed—and/or mechanical equipment, such as for example, piston metering devices, dispensers, centrifugal wheels, etc.

The introduction of the graphite-bearing medium can be managed, for example, by way of the valve opening(s) and/or the inlet opening(s) through which the gaseous medium enters the cylinder chamber.

The introduction of the graphite-bearing medium into the cylinder chamber or chambers can be continuous or discontinuous.

The reciprocating piston compressor can—in accordance with an advantageous embodiment of the reciprocating piston compressor from the invention—have a compressed air supply device through which—preferably with a regulator—the required or desired mass flow of graphite-containing medium is supplied. It is also conceivable, when a specified number of cycles is reached, to introduce a specified quantity of graphite-bearing medium into the cylinder chamber as a precaution.

The invention makes it possible to extend the service life of dynamic seals and to extend their service intervals resulting in a cost reduction, in particular in maintenance costs.

The medium used is comparatively inexpensive in addition and the necessary procedure for supplying it does not require any disproportionately great constructional expense. 

1-9. (canceled)
 10. A method for compressing a gaseous medium, wherein the compression is carried out by a reciprocating piston compressor, a piston of which having a dynamic seal, wherein before and/or during the compression a graphite-bearing medium is supplied to a cylinder chamber of the piston, where the graphite-bearing medium settles on the dynamic seal.
 11. The method according to claim 10, wherein the gaseous medium is hydrogen
 12. The method according to claim 10, wherein graphite dust, molybdenum and/or other dusts or dust mixtures which possess lubricating properties are used as the graphite-bearing medium.
 13. The method according to claim 10, wherein a sealing additive is added to the graphite-bearing medium.
 14. The method according to claim 13, wherein cotton fluffs, mustard fiber and/or other additives which tend to clog and/or clump are used as the sealing additive.
 15. The method according to claim 10, wherein the graphite-bearing medium is supplied into the cylinder chamber by compressed air, the gaseous medium to be compressed, and/or a mechanical device.
 16. The method according to claim 10, wherein the supplying of the graphite-bearing medium into the cylinder chamber is continuous or discontinuous.
 17. A reciprocating piston compressor having a cylinder chamber and a piston with a dynamic seal, wherein means are provided to supply a graphite-bearing medium into the cylinder chamber.
 18. The reciprocating piston compressor according to claim 17, wherein the means to supply the graphite-bearing medium is a compressed air supply device, a device to supply a gas to be compressed, and/or a mechanical supply device.
 19. The reciprocating piston compressor according to claim 17, wherein the means to supply the graphite-bearing medium regulates a mass flow to be supplied.
 20. A reciprocating piston compressor, comprising: a cylinder chamber; a piston with a dynamic seal movable within the cylinder chamber; and a graphite-bearing material disposed on the dynamic seal.
 21. The reciprocating piston compressor according to claim 20, wherein the graphite-bearing material is disposed on an inner wall of the cylinder chamber.
 22. The reciprocating piston compressor according to claim 20, wherein a sealing additive is blended into the graphite-bearing material.
 23. The reciprocating piston compressor according to claim 20, further comprising a compressed air supply device coupled to the cylinder chamber, wherein the graphite-bearing material is supplied to the dynamic seal via the compressed air supply device.
 24. The reciprocating piston compressor according to claim 20, wherein the graphite-bearing material is disposed on a leaking area of the dynamic seal.
 25. The reciprocating piston compressor according to claim 20, wherein the graphite-bearing material is supplied to the dynamic seal through an opening in the cylinder chamber through which a gas to be compressed is supplied to the cylinder chamber.
 26. The reciprocating piston compressor according to claim 20, wherein the graphite-bearing material is supplied to the dynamic seal in a gas to be compressed by the compressor. 